This invention relates to fuzes and more particularly to a fuze for an explosive apparatus that is protected against premature detonation until it reaches the intended target. In heavy tropical-like rain storms the mass of raindrops coupled with their relative velocity with respect to a projectile in flight imparts a sufficient impulse on the point of detonating element to cause premature functioning. Premature functioning is also caused by umbrellas of dense foliage when penetrated by point detonating shells.
The prior structures related to the subject invention is described in U.S. Pat. No. 3,726,228 filed Nov. 23, 1970, issued Apr. 10, 1973 and application Ser. No. 468,723 filed May 10, 1974. More specifically, the Density Integrating Fuze Head described in the reference patent provided cross-bars as a protective shield to prevent premature detonation. In the reference application is shown a twisted cruciform as a protective shield to prevent premature detonation. The cross-bars and the twisted cruciform were used in the fuze head as a mechanical barrier which allowed retaining the sensitivity of the fuze while still exposing the shell to various interferences before impact with the ground. These barrier devices including the relief vents have been particularly well adapted in actual use associated with military fuzes in a tropical environment.
The prior structures, however, have several drawbacks as for example the referenced patent shows various objects are able to by-pass the cross-bars and impact directly on the detonator causing the shell to prematurely explode. The cross-bars cover less than 20% of the surface of the detonator permitting the detonator to be exposed to direct impact. Furthermore, the cross-bars are capable of accumulating water from raindrops and when the volume could not be retained, the water would move directly upon the detonator with a greater mass causing the shell to explode. In addition, under the action of an impact force produced by leaves, limbs and thin branches, a cross-bar is subject to bending and probable dislocation. In fact, the resistance or stiffness of a cross-bar to bending is substantially less than the resistance of a solid protective piece resting at the base since it is susceptible only to compression. When under the action of an impact force a cross-bar is bent towards the closing disc to a deflection equal to its diameter, then the cross-bar slips out from the cross-bar holder and offers no resistance against subsequent impact.
The referenced application uses a twisted cruciform that is inserted and fixed in the cavity similar to the subject invention. However, the cost of manufacture and assembly is considered to be greater than desirable. In addition, the subject invention is an improved diffuser which eliminates the manufacturing problems inherent in the cross-bars and the twisted cruciform design and can be produced at substantially less cost.
Accordingly, the instant invention pertains to a diffuser that sets up a barrier with which the large raindrops collide with the barrier and are broken up into small droplets or atomized and deflected away from the detonating element. In the case of foliage, the diffuser sets up a barrier restraining the foliage from contacting the detonating element and thereby preventing the premature functioning of the shell.